Depth-From-Defocus (DFD) technology determining a distance between an object and an image sensor operates to estimate a distance between the object and the image sensor using a blur size at each of images obtained through a plurality of apertures. However, such general DFD technology is insufficient to exactly calculate a distance between an image sensor and an object because the distance between the image sensor and the object is estimated based on a blurring rate after blurring images and equalizing blur sizes of the images.
For that reason, there has been proposed technology of using a disparity between images obtained through a plurality of apertures in order to determine a distance between an image sensor and an object. In detail, such disparity-based technology operates with two optical systems each including apertures and image sensors, and determines a distance between the image sensor and an object by using a disparity between images obtained by the images sensors through apertures respective to the two optical systems.
With the disparity-based technology requiring two optical systems, it may be inadequate for a scaling-down camera module and may be costly in fabrication.
Therefore, the following embodiments for determining a distance between an image sensor and an object are proposed to solve the aforementioned disadvantages and problems involved in the DFD technology and the disparity-based technology.